In fact, many of the tolerances are closer than on some of the top-drawer imports, Mr. Tasca asserts. True or not, Detroit carmakers face the massive job of convincing motorists that today's US-built cars are at least approaching, or on a par with, the quality of many of the imports - a job that Tasca and Philip E. Benton Jr., Ford vice-president for sales, agree is a tough one.

Further, ''the US auto industry has a bad reputation for service and response to consumer complaints,'' Mr. Benton admits, and millions of motorists, many of whom now own an import, agree.

To counter the image, the domestic car industry is spending tens of billions of dollars to slim down and upgrade its products and put a big ''Q'' back in quality.

Ford president Donald E. Petersen and other Ford top brass are wrapping up a 124-city blitz in an attempt to boost Ford's market share from the current 17 percent of US car sales to 19 percent next year.

Quality now is the ''No. 1 purchase motivator,'' asserts Ford executive vice-president Harold Poling. That's the point the roving Ford team is trying hard to get across. If successful, the company may be able to move more potential car buyers off dead center and into the marketplace in the months ahead.

In pointing the finger at its suppliers in June, Ford said that either they meet the quality level the company has set or go somewhere else to peddle their goods.

General Motors, Chrysler, and American Motors are all drawing a heavy line under quality for 1983. The imports, for the most part, already enjoy a favorable image among car buyers for building good products, yet some of them have had major rust problems over the years. The rust issue, however, seems to taint the imports far less than the domestics.

In setting its sights on '83, Ford alone has spent $3 billion on its new-product program, starting with the light-truck Ranger last spring and winding up with the Ford Tempo and Mercury Topaz, successors to the Fairmont/Zephyr, in the spring.

Whether or not it will get its money's worth depends to a large degree on the economy as well as the believability of its sales pitch.

Up to now Ford, which admittedly has fallen behind General Motors in new-product offerings over the last few years, is trying hard to close the gap. Ford has just launched the downsized Ford LTD and Mercury Marquis, built on the platform of the discontinued Ford Granada, and it also has a Mustang convertible.

The ragtop, which will sell for around $12,000, will have a production capacity for '83 of 25,000, says Mr. Benton, the Ford sales chief.

Last spring Ford introduced the Ranger junior-size pickup truck even though the company lost its '82-model-year truck-sales lead to Chevrolet, one of the few times in the past decade that GM has bested Ford in trucks.

In January Ford will introduce the sharply redesigned and downsized Ford Thunderbird and Mercury Cougar as well as the Bronco II. The downsized Bronco, sharply smaller than the tougher full-size Bronco, is expected to find a major new market among women.

As for the restyled T-bird turbo, ''It will be an honest car, not a head snapper,'' Benton reports.

In April the Ford Tempo and Mercury Topaz will bow.

In striving to recapture a larger slice of the auto market, Benton says that besides bringing out new cars, Ford is tapping its work force for ideas on how to get better models off the assembly line.

As part of his message for '83, Ford president Petersen points to a new style of management which is expected to play an important role in rebuilding the company's strength in the marketplace.

''Improved business performance begins with people,'' he asserts.

The company's goal, he explains, is to turn away from what he calls the ''hierarchical-dictating approach'' of the past to a ''participative-cooperative approach'' where ''timidity has no place.''

Dr. W. Edwards Deming, who played a large part in Japan's postwar automotive success story, has been working for Ford, among other carmakers.

''Management has failed in this country,'' Dr. Deming once said. ''The emphasis is on the quarterly dividend and the quick bucks, while the emphasis in Japan is to plan decades ahead.''

For more than a year, Ford Motor Company has been listening with a sharp ear.